Pensions and Post-Retirement Benefit Plans - Schedule of Pension Plan Assets at Fair Value (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	$ 190.0	$ 208.0
Investments measured at NAV	40.7	37.5
Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	149.3	170.5
Fair Value, Recurring | Quoted prices in active markets for identical assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	0.0	0.0
Fair Value, Recurring | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	97.0	170.5
Fair Value, Recurring | Significant unobservable inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	52.3	0.0
Fair Value, Recurring | U.S. equity securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	7.9	8.1
Fair Value, Recurring | U.S. equity securities [Member] | Quoted prices in active markets for identical assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	0.0	0.0
Fair Value, Recurring | U.S. equity securities [Member] | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	7.9	8.1
Fair Value, Recurring | U.S. equity securities [Member] | Significant unobservable inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	0.0	0.0
Fair Value, Recurring | Insurance Annuity Contract and Other Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	52.9
Fair Value, Recurring | Insurance Annuity Contract and Other Investments [Member] | Quoted prices in active markets for identical assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	0.0
Fair Value, Recurring | Insurance Annuity Contract and Other Investments [Member] | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	0.6
Fair Value, Recurring | Insurance Annuity Contract and Other Investments [Member] | Significant unobservable inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	52.3
Fair Value, Recurring | International equity securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	17.9	19.3
Fair Value, Recurring | International equity securities [Member] | Quoted prices in active markets for identical assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	0.0	0.0
Fair Value, Recurring | International equity securities [Member] | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	17.9	19.3
Fair Value, Recurring | International equity securities [Member] | Significant unobservable inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	0.0	0.0
Fair Value, Recurring | U.S. debt securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	64.9	68.6
Fair Value, Recurring | U.S. debt securities [Member] | Quoted prices in active markets for identical assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	0.0	0.0
Fair Value, Recurring | U.S. debt securities [Member] | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	64.9	68.6
Fair Value, Recurring | U.S. debt securities [Member] | Significant unobservable inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	0.0	0.0
Fair Value, Recurring | International debt securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	3.6	62.7
Fair Value, Recurring | International debt securities [Member] | Quoted prices in active markets for identical assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	0.0	0.0
Fair Value, Recurring | International debt securities [Member] | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	3.6	62.7
Fair Value, Recurring | International debt securities [Member] | Significant unobservable inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	0.0	0.0
Fair Value, Recurring | Cash & Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	2.1	11.2
Fair Value, Recurring | Cash & Cash Equivalents [Member] | Quoted prices in active markets for identical assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	0.0	0.0
Fair Value, Recurring | Cash & Cash Equivalents [Member] | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	2.1	11.2
Fair Value, Recurring | Cash & Cash Equivalents [Member] | Significant unobservable inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	$ 0.0	0.0
Fair Value, Recurring | Other Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets		0.6
Fair Value, Recurring | Other Investments [Member] | Quoted prices in active markets for identical assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets		0.0
Fair Value, Recurring | Other Investments [Member] | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets		0.6
Fair Value, Recurring | Other Investments [Member] | Significant unobservable inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets		$ 0.0